Fuel Tank Pressure Sensor

WARNING: This page is about a different car, the 2011 Subaru Tribeca. However, it is still accessible from the selected car via links, so may be relevant.

Check that the fuel tank pressure sensor has no deformation, cracks or other damages.
Connect dry-cell battery positive terminal to terminal No. 3 and dry-cell battery ground terminal to terminal No. 1, circuit tester positive terminal to terminal No. 2 and the circuit tester negative terminal to terminal No. 1.
NOTE:
- Use new dry-cell batteries.
- Using circuit tester, check the voltage of a single dry-cell battery is 1.6 V or more. And also check the voltage of three batteries in series is between 4.8 V and 5.2 V.
Fig 1: Checking Voltage Of 3 Batteries In Series
Courtesy of SUBARU OF AMERICA, INC.

Check the voltage at a normal atmospheric pressure.

NOTE: The atmospheric pressure at higher altitude is lower than normal. Therefore, the voltage is lower than the standard value.

Terminal No.	Standard
2 (+) and 1 (-)	Approx. 2.5 V (when 25°C (77°F))

Connect the Mighty Vac to the pressure port (A) of fuel tank pressure sensor.

Fig 2: Identifying Fuel Tank Pressure Sensor Port
Courtesy of SUBARU OF AMERICA, INC.
Check the voltage when generating vacuum and positive pressure using Mighty Vac.

CAUTION: Do not apply pressure out of the range of -10 - 20 kPa (-0.1 - 0.2 kgf/cm² , -1.45 - 2.90 psi). Doing so may damage the fuel tank pressure sensor.

Pressure	Terminal No.	Standard
-6.67 kPa (-0.07 kgf/cm² , -0.97 psi)	2 (+) and 1 (-)	Approx. 0.5 V (when 25°C (77°F))
6.67 kPa (0.07 kgf/cm² , 0.97 psi)	2 (+) and 1 (-)	Approx. 4.5 V (when 25°C (77°F))